This invention relates to a work-hardenable substantially austenitic stainless steel having a combination of high strength and high uniform tensile elongation. More particularly, the invention relates to a Cr-Mn-Ni substantially austenitic stainless steel having relatively low amounts of Cr and Ni and having desirable properties developed during cold working over a relatively wide range of cold reduction.
In applications such as the manufacture of automobile seat belt anchors, hose clamps, springs, etc., it is desirable to have an austenitic stainless steel which has uniform elongating properties so that it may be readily stretched without necking. In addition, for substantially austenitic stainless steels of this type, it is desirable that they be hardenable by having the capability of being cold rolled, formed, or otherwise cold worked to very high tensile strength levels. To facilitate production, it is also desirable that such stainless steels exhibit a combination of high strength and high uniform tensile elongation after cold rolling or forming over a wide as possible range of amounts of cold work.
In view of the periodic scarcity and high cost of nickel and chromium, it is desirable to provide an alloy of this type wherein the nickel and chromium requirements are lower than the alloys conventionally used. Specifically, AISI Type 304, 301 and 201 stainless steels may be employed in applications of this type and for this purpose require nickel of 3.5% or above and chromium of 16% or above. Type 201 also requires manganese within the range of 5.perp. to 7.perp.%.
It is, accordingly, an object of the present invention to provide a work-hardenable substantially austenitic stainless steel that has uniform elongating properties in the cold-worked condition, while requiring nickel and chromium at levels lower than conventional alloys used for the purpose.
It is also an object to provide an alloy which is a suitable substitute for AISI Type 201, 301 and 304 steels in structural applications with a combination of corrosion resistance, high strength and high residual elongation when used in the cold-worked condition.
The alloy should also be capable of being produced by a low-cost process.